Thermostat



Sept. 1932- H. D. COLMAN 1,875,369

T HERMO S TAT Filed May 12. 1930 'NVENTOR 4 l fowar'd D- Colman vATTORNEYS Patented sept. 6, 1932 umjrso STATES HPI'ATEN'II? oFFicaHOWARD D. COLIAN, Oil? ROCKFORD, ILLINOIS THERMOSTAT Application filed.Kay 12, 1930. Serial no. 451L579.

This invention relates to thermostats and more particularly to thoseofthe open switch type.

R Thermostats of the above character gen-" free circulation of air aboutthe element.

With the contacts thus exposed, dust and other'foreign particles"carried by the circu- U *tlOIl 1n the drawing includes an elongatedlating air accumulate on the contact surfaces and prevent properengagement thereof which causes undue sparking and burning oil of thecontact points. The sensitivity of the instrument is thereby materiallyimpaired.-

The primaryobject of the present invention is to overcome the aboveobjection through the provision of a new and improved casingconstruction which efl'ectually encloses the thermostat sw itcheswithout decreasing the required circulation of air around thethermo-sensitive element.

In carrying out this object, the control v V switches are enclosedefiectually through the provision'of-a partition separating'thethermostat easing into a lower compartment through which air maycirculate freely and anupper compartment WhiCh "iS completely closedexcept for a narrow opening in the partition through which thethermostatic tongue rojects. 7

Another object secure the partition above mentioned on the removablecover as distinguished from the supporting 'base of thethermostat,'preferably forming the'partition inte a1 with the walls ofthe cover; Other 0 jects and advantages of the invention will becomeapparent from thefollowing detailed description, in which Figure 1 ofthe-drawing is a front elevational view'partially in section of athermostat embodying the features of the present invention.

Fig.,2 is a right side view of Fig. 1 with the cover shown insubstantially central section.

detail in the preferred form and in connection with a particular type ofthermostat, it is to be understood'that modifications and alternativeconstructions made by those skilled in the art to adapt the same todifferent conditions will lie within the scope of the invention asdefined by appended claims.

The thermostat shown by way of illustrabase 5 adapted to be secured invertical position against a flat wall surface and supporting at itslower extremity one end of a coiled strip 6 of bimetallic metal whichconstitutes the thermo-responsive element. Secured to the other end ofthe strip. and projecting upwardly along the center of the base is anelongated fiat tongue 7 whose upper end carries a contact whichcooperates with twofixed terminals 8 to form control switches whichalternately open and close with reversals in the temperature to whichthe thermal element is exposed. The ends of the terminals 8 are,according to the usual practice, spaced close together and confine thelateral movement of the tongue to a narrow range.

\ The operating parts above described are protected against mechanicalinjury by a removable cover having a front wall 9 and a strip 6,.thelowers-portion of the side wall 10 is formed with a seriesof'perforations 12.

Thatportion of the cover enclosing the control switches is unp'erforatedand this end of the compartment is substantially. closed 'througlf theprovision of apartition 13 extending between the two opposite sides ofthe cover somewhat below the contacts 8 and defining the bottom wall ofaseparate switch compartment. To form a more rugged construction, thepartition is mounted on the cover and to this end the latter ispreferably made of molded bakelite so that the partition wall may bereadily formed integral with the side and front walls of the cover as isclearly shown in Fig. 4.

At its center the partition is formed with a slot 1A of a width slightlygreater than the range of movement of the thermostat tongue. This slotopens at the inner edge of the partition so as to receive the tongue 7as the cover is fitted onto the base and guided into proper position bythe shoulder portion 11. With the cover thus positioned, the inner edgeof the partition abuts against the face of the base as shown in Fig. 3.

With this simple construction, the control switches are housed in asubstantially closed compartment from which dust and foreign particlesare eifectually excluded by reason of the fact that the only openinginto the switch compartment is through the lower defining wall thereof,which opening may be made small because of the relatively narrow rangeof motion of the thermostat tongue which projects into the switchcompartment. Casting the partition integral with the cover affords aninexpensive method of forming the partition and avoids the danger ofdislocating the partition and thereby impair ing the thermostat in theact of placing the cover onto the base. Inasmuch as the partition iscarried by the cover, it is removed with the cover and therefore doesnot interfere with the adjustment of the thermostat or cleaning of itscontacts.

I claim as my invention:

1. A thermostat comprising, in combination, an elongated substantiallyflat base, a removable cover composed of molded insulating material andhaving a substantially flat front wall and -aperipheral side wall, saidcover being adapted to fit onto said base and cooperating therewith toform an elongated compartment, a coiled bimetallic strip supported onsaid base at one end of said compartment, an elongated substantiallyfiat tongue supported by said strip and project-- ing longitudinally ofsaid compartment, :1. contact mounted on said base at the end thereofopposite said strip and cooperating with the free end of said tonguetoform a control switch, and a partition molded integral with the coverwalls and extending transversely across the cover to divide saidcompartment into a perforated portion containing said thermostatic stripand an unperforated portion substantially closed by said partition andcontaining said switch, said partition-having a slot therein open at itsinner edge so as to receive said tongue when said cover is fitted ontosaid base.

2. A thermostat comprising, in combination, an elongated base,athermo-sensitive element mounted on one end of said base,

a circuit terminal mounted at the other end of said base, an elongatedtongue extending longitudinally of the base and having one endassociated with said element and the other end cooperatingwith saidterminal to form a switch, a casing enclosing the device and having theportion thereof adjacent said bimetallic element perforated to permitfree circulation of air therethrough, the remainder having solid walls,and a partition cast in tegrally with said casing dividing saidperforated from said unperforated portions to form a substantiallydust-proof compartment for said switch, said partition having a narrowslot receiving said tongue when said casing is placed on said base.

3. A thermostat comprising, in combination, an elongated base, a coveradapted to fit on and cooperating with said base to form an elongatedcompartment, a partition formed integral with said cover and dividingsaid compartment into a substantially closed portion at one end, thewalls defining the compartment being perforated to permit thecirculation of air through the other end portion ofthe compartment, athermo-sensitive element mounted on said base in said open end portion,an elongated member arranged to be actuated by said element andextending longitudinally of said compartment through said partition intosaid closed portion, and a contact within the closed portion of saidcompartment cooperating with said tongue to form a control switch.

4. A thermostat comprising, in combination, an elongated base adapted tobe mounted in an upright position, a bimetallic strip responsive totemperature variation and mounted at the lower end of said base, acircuit terminal mounted at the upper end of said base, an elongatedtongue extending longitudinally of the base and having one end rigidwith said bimetallic strip and the other end cooperating with saidterminal to form a switch, a casing formin a cover for the device, thelower portion of said casing enclosing the bimetallic element havingperforations to permit free circulation of air therethrough, theremaining lower portion being unperforated, and a partition within saidcasing dividing said perforated from said unperforated portion to form asubstantially closed chamber for said switch, said partition having anarrow slot through which said tongue projects.

5. A thermostat comprising, in combination, a casing defining anelongated c0mpartment, a partition extending transversely of saidcompartment and dividing the same into a substantially closed portion atone end, said casing having at its other end portion a perforated wallpermitting the circulation of air therethrough, an elongated switchactuating member projecting longii tudinally of said compartment throughan 0 Jening in said artition, a thermo-sensitive eiement mounte in theopen end portion of said compartment and arranged to actuate saidmemJer, and acontact mounted in the closed end portion of saidcompartment and cooperating with said control'sw1tch.

6. An automatic control device for air conditioning systems comprising,in combination, an elongated casing having perforated walls at one endthereof so as to permit the free circulation of air therethrough, a,partition extending across said casing near the other end thereof andcooperating wit-h member to form I a such end to form asubstantiallyclosed compartment, a contactswitch disposed in said closed compartment,an element responsive to changes in the condition of the circulating airand mounted 1n the end of said casing opposite said compartment, and anelongated member extending longitudinally of,

the casing through said partition having one end associated with saidelement and the other end arranged to actuate said switch in response tosaid element.

7, A thermostat comprising, in combination, acasing comprising twoseparable parts adapted when assembled to define a chamber having onesection defined by closed walls and another section defined by wallsperforated to permit air circulation therethrough, thermostatic meansinsaid last mentioned section including an elongated member laterallymovable as an incident to temperature changes, a. contact in said closedsection cooperating with said member to form a control switch, saidcontact and thermostatic means being mounted on the same one of saidparts to permit adjustment of the thermostat prior-to assembly of theparts. and a.

partition between the sections of saidchamber' havmg an aperture thereinadapted to receive said member as an incident to assembly of Silld partsandof a size permit-- ting of the necessarv lateral movementof saidmember.

In testimony whereof, I have hereunto affixed my signature.

HOWARD D. comma.

